MEMS Thermal Flow Sensor with Enhanced Sensitivity by Multi Channel Data Acquisition

In this study, we report a microelectromechanical systems (MEMS) thermal gas flow sensor and propose a signal processing strategy under hot-wire operating mode. The sensor is designed as a dual-chip integration. The thermistors on the dual chips form a Wheatstone bridge to improve the sensitivity. A data acquisition strategy based on the designed multiplexed signal interface circuit is proposed to enhance the performance of the sensor in the micro flow range (0~3ml/min). The results show that the sensitivity of the sensor is improved by 2.5 times in the range of 3 ~100 ml/min. In the range of 0~3 ml/min, the sensitivity was increased by a maximum of 26 times. The detection limit was reduced from 0.5 ml/min to 0.2 ml/min. Besides, the strategy was implemented in the microcontroller without changing the sensor's operating state, which avoids the problem of delay time caused by multi-mode switching. This work provides new design ideas for MEMS thermal gas flow sensors to meet the needs of different applications.